- Have taken any of the following within 6 months before study entry: interleukins, interferons, therapeutic HIV vaccine, thalidomide, pentoxifylline, dinitrochlorobenzene (DNCB), thymosin alpha, thymopentin inosiplex, polyribonucleoside, ditiocarb sodium, hydroxyurea, systemic corticosteroids, azathioprine, 6-mercaptopurine, cyclosporin A, or any investigational drug.